The thallus grows in irregular shapes or rosettes up to 5 cm (2 in) in diameter, with olive-green to greenish-brown coloration and elongated lobes featuring black, hair-like cilia along their edges.

In his original description, Acharius summarised the main characteristics of the new species, noting that the thallus is pale brownish with a whitish, reticulated-lacunose underside.

He emphasised two key diagnostic features that remain important today: the crisped, ciliate lobes with thick black cilia or granules along their margins, and the cartilaginous thallus texture that becomes more reticulated-lacunose with age.

The study revealed that Cetraria ciliaris produces olivetoric and physodic acids and is found in eastern North America and Finland.

The species is morphologically similar to Cetraria halei, which produces alectoronic acid and has a broader geographic distribution, including the Old World from Finland through the Soviet Union to Japan.

A key aspect of the study was the finding that environmental factors do not significantly influence the chemical composition of these lichens.

[8] Using a phylogenetic approach that incorporated estimates of when different groups evolved over time, researchers proposed that certain genera, including Tuckermannopsis, should be merged with Nephromopsis.

Tuckermannopsis ciliaris is a foliose lichen that typically forms loosely attached, irregular to rosette-shaped growths, reaching up to about 8 cm (3 in) in diameter.

[14] The lobes comprising the thallus (the main body of the lichen) are elongated and range from 1 to 4 mm in width, with a slightly wrinkled surface.

[15] The upper surface of the thallus varies in color from pale to dark greenish-brown, and it lacks pseudocyphellae, which are tiny pores sometimes found in lichens.

[12] Additionally, Tuckermannopsis ciliaris has small, black, protruding structures along the margins called pycnidia, which produce conidia (asexual spores).

In North America, it is found from southeastern Canada to the Lake States and south throughout the Appalachian Mountains and associated foothills.